The Seismic Dynamic Response Characteristics Of The Shaking Table Test On Horizontally Layered Slope

In China, the mountainous area accounts for about2/3of the total land area,including a large number of natural slope and artificial slope, and our country is theworld’s largest land seismic zone, which located in the circum-Pacific seismic belt andthe Mediterranean-Himalayan seismic belt, and seismic is very frequent and widelydistributed, which induces a lot of earthquake secondary geological disaster.Earthquake leading to the slope deformation damage, speeding mountain environmentto a vicious cycle, caused the main reason for the collapse, landslides and othergeological disasters.512Wenchuan earthquake which occurred in2008inducedthousands of collapse and landslides, resulting in a large number of casualties andhuge economic losses. Therefore, Understanding the deformation and failure processof slope under strong earthquake and revealing the deformation and failurecharacteristics and formation mechanism and dynamic response law of slope hasimportant theoretical and practical significance.Based on the typical crack-level-slip landslide in512Wenchuan earthquake, wesimplify its geological conditions, and in combination with the shaking table modeltest of the homogeneous slope, this paper is doing the shaking table test on theHorizontal layered structure rocky slopes. Through observing and recording thephenomena of deformation and failure on the slope during test mode, collectingacceleration response data of the measuring point under seismic loads on the slope,and studying its processing and analysis the instability failure mechanism and slopethe dynamic response characteristics and the law of the horizontally layered slope,providing a reasonable explanation and theoretical support for large landslide collapsein Wenchuan earthquake, and to provide a scientific basis for the strong earthquakeslope stability analysis and structural seismic design. By analyzing the deformationand monitoring data of the test results, combined with the deformation and failure phenomena of the slope in the earthquake zone, to find dynamic response law of thelayered structure slope, the main aspects of the results achieved.Characteristics and formation mechanism of slope deformation and destruction:the action of slope deformation and failure mainly and firstly occurs in the top half ofthe slope under seism action. Deformation of soft rock slope failure is given priorityto cracking-shearing slippage damage, causing obvious crush zone in the center of theslope. With collapsibility of a large number of rock, the deformation and failure ofHard rock slope is later than the deformation and failure of soft rock slope.Contrasting different earthquake parameters under the condition of slope deformationand failure phenomena, it can be found that horizontal seismic force is a major causeof slope failures, and slope deformation damage aggravated with the increase ofvibration strength. In conclusion, with collapsibility of a large number of rock,deformation and failure of horizontal layer slope is given priority to cracking-shearingslippage under seismic action.Seismic dynamic response rules of horizontal bedded slope: after comparing andanalyzing response acceleration of measuring point under different seism action, thebased on the and different seismic load under the action of the acceleration responseof point data comparison and analysis of a dynamic response acceleration of slopeunder the condition of different parameters change curve, the result shows the changetendency of the parameters. by means of the parameters, the paper studies the slopedynamic response rule of acceleration and probes into the effect of the slopetopography conditions, structural plane, elevation, rock conditions, seismic wavetypes and parameters on the seismic dynamic response rules of the slope. Through alot of analysis and comparison, it comes to a conclusion that under the seism actionhorizontal bedded slope has the amplification-directivity effect(free face effect) andelevation amplification effect, lithological effect, directional effect and the effect ofthe structural plane.Free face effects: slope owns free face amplification effect under different seismaction, the location and degree of that is affected by the lithology condition, slopeheight, the types of seismic wave and parameters, and horizontal layer affects the freeface effect of sine wave sticking straight up in the level of Z markedly.Elevation amplification effect: Elevation amplification effect obviously underdifferent seismic action, and is mainly embodied in the top half of the slope(exceptsine wave Z); the degree slope elevation amplification effect decreases with the order:Synthetic natural wave, one-way natural wave, sine wave sequence, synthetic natural wave action to the maximum magnification slope is5.5(soft rock ramp slope inside),one-way natural wave maximum magnification is4.5(soft rock ramp slope inside),sine magnification relatively concentrated in about2.2.Lithological effect: under different seismic load, slope dynamic response of hardrock mainly displays in the bottom of the slope, and soft rock slope mainly displays inthe upper portion of the slope; Under sinusoidal wave action, hard rock slope mainlyshows vertical tension and compression, and soft rock slope with horizontaltenso-shear effect significantly; The response of the slope under the action of naturalwave affected by the earthquake intensity is obvious.Direction effect: under the action of vertical sine wave, the acceleration responseof the slope decreases with increasing frequency, the acceleration response valuewhen the frequency is15Hz is only half when the ramp is5Hz, indicating that duringthe propagation of seismic wave attenuation significantly higher frequency, thequicker the decay; the slope showed a significant effect of P-Δ in synthetic naturalwave, it is also mean that the vertical seismic action can strengthen the influence ofearthquake dynamics, increasing acceleration dynamic response of the slope upward.Structural plane effect: with homogeneous slope test result under the action ofstrong earthquake and comparison of the rocky slope dynamic response accelerationdata whether contain structural plane shows that: under different seismic loads, thelevel of amplification factor in horizontal and vertical direction of the slopes greaterthan1.0basically, that means the level of acceleration dynamic response of theHorizontally layered slope are present amplification, the upward slope in thehorizontal magnification factor of the maximum level of1.35(sinusoidal wave) and1.58(natural wave), the ramp-up in the vertical dimension maximum amplificationfactor of1.53(sine wave) and4.0(natural wave), the result showed that the levelstructure impacting vertical seismic is more significant.